6.4 Potential failure pathways
The potential failure pathways assessed for UMG TSF are presented in Appendix B. The failure pathways are considered credible but the consequence and likelihood of failure for each have not been assessed.
6.5 Mitigation strategies
Discussion on mitigation strategies for the identified failure pathways is presented in Table 6.3.
Table 6.3
Mitigation Strategies for identified failure pathways
Mitigation strategy Description
Responsibility
Planning and design
Comprehensive geotechnical investigation to identify and characterise weak / loose / permeable foundation zones, defects and soil parameters through drilling, sampling and lab testing. Supports stability, seepage and settlement assessment. Develop a geological model using available survey, aerial imagery and geotechnical investigation to understand subsurface variability.
Geotechnical investigation
Heritage / WSP
Geological ground model
WSP
Model seepage pathways through embankment and foundation; evaluate hydraulic gradients and required controls. WSP
Seepage assessment
Analyse embankment stability under static, seismic and post seismic pore pressure conditions.
Slope stability assessment
WSP
Assess flood levels, spillway capacity, water balance, DSA requirement, return water pump sizing, and impacts on freeboard and overtopping risk. WSP Apply appropriate safety margins for freeboard, loading, material tolerances and uncertainties. Specification of materials and development of a technical specification. WSP Design upstream geomembrane liner to limit seepage; extend and anchor beyond abutments. WSP
Hydraulic assessment
Engineering design
Lining system
Additional freeboard above flood level
Provide additional freeboard above design flood level to accommodate settlement and wave run up. Identify and design appropriate spillway arrangement for extreme flood events for closure. Design stable and serviceable access routes supporting TSF operation and monitoring Develop preliminary closure approach consistent with long term stability and seepage controls.
WSP
Closure spillway
WSP
Access / haul road design
Heritage
Conceptual closure design
Heritage / WSP
Construction
Project No PS213278 Upper Mundic Gully - Tailings Management Plan Mount Morgan Gold Mine Heritage Minerals
WSP March 2026 Page 11
Powered by FlippingBook